Thermostatic switch



Jan. 2, 1934. D. s. TAYLOR 1,941,502

' THERMOSTATIC SWITCH Filed June 18, 1931 2 Sheets-Sheet l I NVENTOR DANIEL. G. TAYLOR Q/ Q. 1 91,4 M

A 'O NEY5 Jan. 2, 1934. D. G. TAYLOR 1,941,502

THERMOSTATIC SWITCH Filed June 18, 1931 2 Sheets-Sheet 2 7 INvEN R DANIEL 6. TAYLOR I By @4494 M ATTOPNEY Patented Jan. 2, 1934 THERMOSTATIC swrrcn Daniel G. Taylor, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application June 18, 1931. Serial No. 545,227

6 Claims. (Cl. 200-138) This invention relates to improvements in electrical switches of the thermal or pressure controlled type and to -the provision of means for controlling a switch in a manner to cause it to quickly make and break its circuit.

It is among the objects of this, invention to provide means for applying a biasing force to the switch; to apply such force alternately in opposite directions; to gradually increase the force 10 during motion of the switch; to provide means for preventing the motion of the switch (or of a switch control element) during application of the biasing force whatever the direction of application may be; and .to provide means for releasing the motion-preventing means (or latch) to permit motion of the control element after the biasing force has reached its maximum, or after the conditioning of this force to act.- Other objects relate to provision of means for accomplishing one or more, or any combination of the above objects, and the provision of durable and efficient constructions which can be cheaply manufactured for the purposes herein.

Features of the invention include the details as disclosed, along with the broader ideas of means of the disclosure, relating to the application of the biasing force and to the tripping of the latch while the force is acting, whether the latching and biasingdome-application be in one or both directions, or whether the biasing force be applied by the switch per se, or by an'element other than the switch.

Other objects, features and advantages of the invention will be set forth in the description of the drawings forming a part of this application, and in said drawings Figure 1 is a vertical section through a thermostatic device (stack switch) showing one embodiment of the invention;

Figure 2 is a face view of the switch mechanism showing the positions of the parts prior tolatch release of the switch arm for closing the switch, and with the control element at the peak of the cam and moving in clockwise direction;

Figure 3 is a view similar to Figure 2 showing corresponding positions of the parts prior to opening the switch, and with the control element moving in counter-clockwise direction; and

Figure 4 is an enlarged detail, illustrating the relation of the control element to the cam.

The invention herein is shown applied to a stack thermostat in which two switches are controlled by a commori thermal means so that on the movement of temperature in one direction, the switches are moved to one switch control position and so that on movement of temperature in the opposite direction, the switches are moved to the opposite control position. In the device as shown only one of the switches is controlled in accordance with the teachings of this invention. The device herein finds valuable application at present for controlling burner apparatus.

The main object of the invention is to provide means whereby a single switch can be socontrolled that it will make and/ or break its circuit quickly.

Numeral 1 indicates a suitable casing for housing the switch or switches as well as part of the means for controlling them. Numeral 2 indicates a cover for the casing. Suitably attached to the outside of the back of the casing perpendicularly thereto is a tubular member 3 which is adapted to pass through the wall of a stack, and to be suitably secured thereto by a bracket 5. Within the tubular member is a shaft 6 suitably journaled at one end as at 7, the shaft projecting beyond the bearing 7. The shaft is journaled at the opposite end as at 8 in the rear wall of the casing 1 and projects into the casing. Attached to the shaft 6 is the usual thermostatic element 10 in the form of a spiral ribbon having one end connected as at 11 to the tube and having the opposite end connected as at 12 to the shaft 6. On temperature changes, the rod is rotated conformably to expansion or contraction of the element 10.

Mounted upon the shaft within the casing are, in this instance, two switch control elements, one only of which is controlled by the invention herein, although it is obvious that both could be so controlled. Two spur gears or toothed disks, or equivalent devices, providing spaced stops, cooperate to move respective switch members, a certain distance, after which each is maintained in its particular switch-control position, although motion of the disks may continue in the same direction. Two disks are employed, one fixed and one rotatable relative to the shaft 6. The action of the toothed disks in controlling the switch arms is fully described in the patent to Cyr No. 1 0 1,768,892, issued July 1, 1930. The disks are mounted on the shaft in the following manner:

The shaft 6 is counter-turned or reduced as at 13 and this reduction provides a. shoulder 14. The outer end of the reduced portion is threaded 1 as at 15. Arranged on the reduced portion and abutting the shoulder and secured to the shaft is a sleeve 16, and also arranged upon the reduced portion is a sleeve 17 of insulating material which abuts the sleeve 16. Upon the element 17 is a 0 cup-shaped insulating member 18 which abuts the element 16. Mounted on the insulating sleeve 1'7 is a toothed disk 20, and abutting this disk and also mounted on the insulating sleeve 1'7 is a sleeve 21 having a reduced terminal portion 22 providing a shoulder 23. Upon this reduced portion is rotatably mounted a toothed disk 25, and also rotatably mounted on this reduced portion is a plate 26 which is slotted as at 2'7. Passing through the slot and threaded into the disk 25 are set screws 28. The plate 26 is segmental and covers only a portion of the face of the disk and provides at one side a radial portion 29 as a stop. The disk 25 is slotted as at 30 and one end of the slot forms a stop 31. The disk 20 carries a pin 32 which passes loosely through the slot 30 and may engage either the stop 29 or 31. according to the direction of rotation of the shaft 6, and after a certain degree of rotation, as determined by the spacing of the stops. The lost motion connection may, therefore, be varied.

The disk 20 is frictionally held for rotation with the shaft in the following manner: Abutting the outer end of the sleeve 21 is a washer 33 and abutting this washer is a cup-shaped insulating member 34. The washer and insulating member are both mounted upon the insulating sleeve 1'7 and the inner vertical face of the cup washer 34 is spaced slightly outwardly beyond the end 35 .of the insulating sleeve 17. Engaging the inner face of the cup is a washer 3'7 and abutting this washer is a split spring washer 38, and a nut 39 cooperating with threads 15 engages the washer 38. By means of this nut, thrust is applied through washers 38-3'7, cup 34, washer 33, sleeve 21 to disk 20 which is, in turn, pressed against the cup 18, the cup being, in turn, pressed against the element 16.

By adjusting the distance between the stops 29 and 31, the degree of lost motion between the disk 20 (and, therefore,the shaft) and the disk 25 can be obtained. It is obvious that the parts may be so adjusted that shoulders 29 and 31 both engage the pin 32 so that the disk 25 moves with the disk 20 and, therefore, with the shaft in a fixed relation thereto. On clockwise motion of the shaft 6, the fixed disk 20 moves a certain distance until the pin 32 engages the shoulder 29. When the shaft moves in counter-clockwise direction, this movement is delayed until the pin 32 engages the shoulder 31.

Suitably attached within the casing 1 is a block 40 of insulating material. To this block are at tached, see Figures 2 and 3, two plates, respectively indicated 41 and 42. On the plate 41 is mounted a flexible contact arm 43 and on the plate 42 is mounted a flexible contact arm 44. Suitably secured to a common support 45, in turn mounted on the insulating block 40 is a flexible contact arm 46 having a contact stud 4'7 engageable with the flexible arm 44. The arm 46 is biased to move toward contact arm 44 or towards closed circuit position. Associated with the arm 46 is a flexible control arm 48 having an opening 49 through which the stud 4'7 loosely passes, see Figure 1. The control arm 48 is engaged with the teeth of the disk 20 and with the parts positioned as in Figure 2, this control arm holds the switch arm 46 in open position from'which position it will automatically follow the element 48 when this element is moved to the right by a counter-clockwise rotation of the disk 20, and on continued motion the stud 47 will assume closed circuit relation with element 44 after which the control element 48 moves away from the contact arm 46 on continued rotation of the disk 20 in the same direction, in this instance as the temperature continues to rise. During this continued motion, the control element 48 is successively released and moves against the follow ing disk tooth as a stop, but without suflicient movement to permit the control member to move the switch arm from its closed-circuit position.

The contact arm 43 is controlled by the following mechanism which illustrates one embodiment of this invention and which, in this instance, includes a flexible switch control element 52 secured as at 53 to resilient switch arm 62. Element 52 has an opening 56 through which loosely passes a spring metal arm 5'7 attached only at one end as at 58 to the end of an extension 59 of bracket 45. The spring metal arm is provided intermediately with a'cam 60, in this instance convex toward the shaft and toward the free end of the switch control member 55. The cam is formed by bending the spring arm. The spring contact or switch arm 62 has a contact stud which engages the arm 43 to close the circuit. The spring contact arm 62 is terminally provided with an angularly bent portion 65 facing in a direction away from the end of the spring latch arm 5'71 The end of this spring arm 57 'has a downwardly bent latching portion 66, adapted when the element 62 is in switch closed position, see Figure 3, to be so positioned 105 that on slight depression of the spring arm 5'7 it will assume a latching relation to prevent opening movement of the arm 65. On the other hand, when the switch element 62 is in open position, the hook or latch 66 is adapted, on depression of the arm 5'7, to engage the end of the extension 65 to secure the switch in open position. v The latch arm 5'7 automatically assumes a position at which extension 65 lies outside of the motion path of the switch arm 62; that is automatically assumes this nonlatching position.

The plates 41 and 42 are connected by con ductors respectively indicated 67-68 with corresponding binding posts 69-70. The bracket 45 is connected by a conductor element '71 with 120 binding post 72. These conducting elements are embedded in the block of insulating material 40.

The spring latch arm 5'7 is operated by the control element 52, and it is among the objects herein to provide a movable latch element adapted to 125 secure the switch (or switch control element) in either of its control positions, and to provide means for applying a biasing force to the switch (or control element) to move itto either control position, and to provide means for automatically 130 releasing the latch element after biasing force has been applied in the appropriate direction, or after the resilient switch arm has been flexed in the appropriate direction.

Operation The operation is as follows: Assume the switch to be open, and a cooling motion of the shaft to take place. Pin 32 engages shoulder 29 and disk 25 moves in clockwise direction, see Figure 2. The control element 52 is at the right hand side of the cam. The control element continues to move to the left and engages the cam and depresses the spring latch arm 57, bringing the latch to the position shown, to prevent closing of the switch. After the latch has engaged the switch arm and on continued motion of the control element, in the same direction, the switch arm is being put under tension or is being biased so that it will snap to closed circuit position, as 150 spring latch arm. The-spring arm begins to move in release direction as soon as the control arm passes the peak of the cam and since the motion of the control arm is slow, the release motion of the latch is also slow. However, when the latch arm has moved sufilciently, the switch arm is released and is snapped to closed position under a maximum or biasing force, which was set up during the movement of the control element. When the switch arm 62 has moved to its closed position, it lies at the left of detent 66 so that on suillcient flexure of the arm 57, detent 66 will move into the path of the arm 62. After switch closure, motion of both disks may continue in counter-clockwise direction without affecting the position of the switches which they control.

On reverse motion of the shaft, or on motion in counter-clockwise direction, and after pin 32 has engaged stop 31, disk 25 moves arm 52, now at the left of the cam, and finally the arm engages the cam and depresses the latch so that it assumes latch DOSitiOILsSBG Figure 3. This depression occurs early in the movement, and as the movement is continued, a greater depression of the spring arm 57 takes place, and at the same time, a biasing force isapplied to the switch in direction of opening, and this force steadily increases, all as previously described. 'AIter passing the peak, the latch element is gradually released (if motion of the control element 52 is gradual) and the switch is finally released, while the biasing force is at its maximum, to cause it to snap to open position.

It will be noted that the control arm first engages the cam, and that during the travel of the control arm, the latch arm is flexed to bring the detent to latching position. -By the time the con-' trol element reaches the peak of the cam, latching has been accomplished. During the motion of the control element, the switch element has been biased for movement in the appropriate direction, and against the detent. The biasing force is always being increased while switch arm is latched against motion, whatever be the direction. The cam action and latching action-is substantially the same in both directions.

In some instances, the resilient switch element may itself be biased in one direction, for example, to move by its own resiliency to open position. In any event, the switch control-element is held at its limitcontrol positions by means of the cam, which thus acts as a stop to prevent accidental motion of the control element in either direction when the disk 25 is not being positively moved by the pin 32 in engagement with one of the stops 29 or 31. However, no matter what direction of rotation of the disk or what direction of movement of the control member, even though the switch arm itself be biased to move automatically to one of its control positions, the switch element itself is submitted to. an extra biasing force after it has been latched, and this biasing force is increasing while the control element is moving to latch release position.

Another valuable feature relates to the arrangement whereby opening or closing snap action of the switch is obtainable by a continuous- 1y but slowly moving control element. In this instance, this element is controlled by a slow motion thermostatic element. Whatever the direction of motion, the biasing force can be either slowly or quickly built up during the motion, and this force is at its maximum when the latch is tripped. The release of the latch element can be a slow release and it will be noted that after the control element has passed across the peak of the cam, the continued motion, although it may be slow, gradually releases the latch, the biasing force being continually applied until the latch release takes place.

I claim as my invention:

1. A switch arm, a latch independently mounted and adapted to hold the switch arm against motion, said latch being biased to move automatically away from latching position, and means attached to said switch arm and movable therewith for applying a biasing force,to the arm and having means for tripping the latch while the force is being applied.

2. A switch arm, a latch for holding the arm against motion and means attached to the arm adapted on motion to sequentially move the latch to arm-securing position, apply a biasing force to the arm, and trip the latch while the force is being applied.

3. A switch arm, latch means including a hook holding the arm against motion and a cam, and 108 means movable with the arm and cooperable with the cam to sequentially move the latch to armsecuring position, apply a biasing force to. the arm, and trip the latch while the force is being applied.

4. A contact, a switch arm engageable with said contact and biased to automatically move to switch-closed position, a resilient latch element adapted during flexion to move into switchlatching position, an arm attached to said switch arm, said latch having a cam and said control arm being engageable with the cam to move the latch to latching position and thereafter release the latch while the arm is moving toward either control position.

5. In combination a switch control element, a resilient switch arm mounted on the control element, latching means for holding the switch arm in either oi! its control positions, means for operating the latching means as the result of motion of the control element to move the latch to latching position and trip the latch on continued motion of the control element, said control element being adapted to apply a biasing force to said switch in the same direction as the direction of motion and to continue application of said biasing force while the latch is tripped.

6. In combination a switch control element, a switch arm movable with the control element, latching means mounted independently of the control element and switch arm and adapted for holding the switch arm in either control posi-' tion, means for operating said latching means as the result of motion of the control element to move the latch to latching position and to trip the latch on continued motion of the control element in the same direction, said control element being adapted to apply biasing force and to continue application while the latch is tripped.

, V I DANIEL G. TAYLOR. 145 

